Acute myeloid leukemia (AML), also known as acute myelogenous leukemia, is a clonal proliferation of malignant hematopoietic precursor cells. These immature myeloid cells (myeloblasts) accumulate in blood, bone marrow, or other tissue and cause decreased production of normal blood cells. It is the most common form of acute leukemia in adults. AML is generally rapidly fatal if not treated with intensive chemotherapy and/or targeted therapy.

AML has subtypes and several different gene mutations. Diagnosis usually requires the presence of more than 20% myeloblasts in the peripheral blood or bone marrow; however, several subtypes (with specific cytogenetic / molecular findings) may be diagnosed with less than 20% myeloblasts present. Blast threshold is an area of some contention, with recent key diagnostic criteria differing on its role. The World Health Organization (WHO) 2022 criteria eliminate the 20% blast requirement for most AML-defining genetic mutations (with the exception for BCR:ABL1 and CEBPA), whereas International Consensus Classification (ICC) 2022 requires 10% or more blasts for AML with recurrent genetic abnormalities. Rarely, AML patients may develop myeloid sarcoma tumors (single or multifocal), which can manifest without blood or bone marrow disease. Myeloid sarcoma can precede AML by months to years, occur concomitantly, or follow after AML diagnosis or remission.

The median age at diagnosis for AML is 68-71 years, with a male predominance. Pediatric AML can occur at any age range but is much less common than in adults. AML in pediatrics is often caused by major structural chromosomal abnormalities (such as the KMT2A mutation), as opposed to small sequence mutations as seen in adults. Additionally, pediatric AML is often de novo and not secondary to other bone marrow disorders, such as myelodysplastic syndrome as seen in adults. Because pediatric patients are generally healthier than adults and have fewer comorbidities, they can tolerate more intensive chemotherapy. Pediatric 5-year survival rate is 65% compared with 30% for adults.

Risk factors for AML in pediatric patients include Bloom syndrome, Kostmann syndrome, myelodysplastic syndrome, Fanconi anemia, and trisomy 21 (children with Down syndrome are at greater than 100-fold increased risk for AML).

Related topics: acute myelomonocytic leukemia, chronic myelogenous leukemia, leukemia cutis, oral leukemic infiltration